This invention relates to a method of and an apparatus for supplying oil to a two-stage rotary vane vacuum pump which has pumping chambers, locations to which oil is to be applied, as well as an oil sump.
In oil-operated rotary vane vacuum pumps, one function of the oil is to provide, in the pumping chambers, a sufficient seal between the suction side and the pressure side. At the same time, the oil serves for lubricating the rotor disposed in the pumping chamber as well as the vanes sliding in the rotor. Further, the circulated oil serves for cooling components, particularly those which rotate in a vacuum. In addition, the oil serves to carry dirt particles into the sump. Also, further bearings of the vacuum pump (rotor bearings, drive shaft bearings and the like) are lubricated with the aid of the oil in the vacuum pump.
It is known to provide rotary vane vacuum pumps with a separate oil pump and to introduce the pressurized oil, delivered by such additional pump, to those locations of the vacuum pump which are to be supplied with oil. Although a sufficient oil supply of such locations is ensured, this solution is complex and expensive because it requires a separate oil pump.
It is further known to utilize the vacuum generated by the pump to deliver the oil. In such a solution, however, problems are encountered with the oil supply of those locations which are not situated immediately at the pumping chamber or which, based on the desired pump output, must not be connected with the pump chamber.